Signaling system.



No. 717,771. P'ATENTBD JAN. 6,1903; H. SHOE-MAKER. SIGNALING SYSTEM.APPLICATION FILED AUG. 13, 1902.

K0 MODEL.

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w vtmelswo WW7 A UNITED STATES PATENT OFFICE.

HARRY SHOEMAKER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THECONSOLIDATED WIRELESS TELEGRAPH AND TELEPHONE COMPANY AND MARIE V.GEHRING, OF PHILADELPHIA, PENNSYLVANIA.

SIGNALING SYSTEM.

SPECIFICATION forming part of Letters Patent No. 717,771, dated January6, 1903.

Application filed August 13, 1902- Serial No. 119,468. (No model.)

To aZZ whom it may concern:

Be it known that I, HARRY SHOEMAKER, a citizen of the United States,residing at Philadelphia, in the county of Philadelphia and State ofPennsylvania, have invented anew and useful Signaling System, of whichthe following is a specification.

My invention relates to electrical signaling systems, more especiallythose in which the no energy representing the message or signal istransmitted through the natural media in the form of electromagneticwaves or other electroradiant energy.

My invention resides in the employment of :5 a radiating conductor orconductors in connection with which there is no earth connectionwhatsoever, In long-distance telegraphy heretofore where electromagneticenergy was employed the earth connection was found to be very essential.In my system, however, such earth connections are dispensed with and Iam enabled to transmit messages over great distances with greatfacility.

My invention comprises both transmitter and receiving circuits andapparatus in which the aerial conductor employed is a half or a fullwave length of the energy employed in the system in length.

My invention comprises a method of and 0 apparatus for impressing uponthe natural media electroradiant energy of a certain frequency andreceiving such energy in a receiving-circuit without resorting to theusual ground or earth connections for radiating and receivingconductors.

By my method and apparatus the radiating and receiving conductors areone-half or a full wave length in length and are entirely-insulated fromthe earth. It is often of the nt- 0 most consequence in wave telegraphyas heretofore practiced that a very good earth connection be obtained.In some instances this is very difficult-as, for example, on a rocky,very sandy, or dry shore, and more especially at stations located in theinterior of the country and where the transmission is to take place to agreat extent across land. By my method, however, these earth connectionsare dispensed with, and signaling is easily maintained by the system andappara 5o tus about to be described.

Referring to the accompanying drawings, Figure l is a diagrammatic Viewof a transmitter-station in which the circuit of the radiating-conductorhas a length equal to the length of a wave of electroradiant energywhich is transmitted from it. Fig. 2 shows a diagrammatic arrangement ofthe receiving apparatus in which the receiving-conductor and itscircuits is of a length equal to the length of a wave of the radiantenergy received upon it. Fig. 3 is adiagrammatic view of the transmitterin cases Where the aerial conductor and its circuit is equal to one-halfthe length of a wave as radiated from it. Fig. 4 shows a diagrammaticview of the receivercircuit in which the receiving-conductor is one-halfthe wave length in length.

In Fig. l, B represents a source of energy which when key K is depressedcauses cur- 7o rent to flow through the primary 1:: and the interrupterI. This interrupter I is, for example, a mechanically-driven one andserves to interrupt the current-flow through the primaryp at a highrate. This intermittent cur rent in the primary 19 causes induction inthe secondary s of high-potential currents, and such secondary 3 servesto charge the condenser C, which is in series with the second primary P.In shunt to the secondary s is a spark-gap G, which, along with thecondenser O and the primary P, forms a freely-oscillating circuit, inwhich there occur oscillations of high frequency upon the discharge ofcondenser O. The rate of these oscillations depends upon the electricalconstants of the circuit C P There are then forced vibrations in thecircuit A S A, of which S is, in fact, the secondary of a transformer,and of which A is the usual aerial conductor, and of which A 0 is anidle length of conductor insulated from earth.

Suppose it is desired to transmit electroradiant energy of a frequencysuch that the wave length is six hundred feet. I then de- 5 sign thecircuit A S A so that A is one hundred and fifty feet in height, thatthe winding S is slightly less than three hundred feet in length, and sothat the conductor A is one hundred and fifty feet in length. Thislastmentioned conductor A is for convenience rolled into a bundle andinsulated from earthas, for example, by being immersed in a vessel ofoil or other insulatingmaterial. I have said that the length of thewinding S is slightly less than three hundred feet. This I find to benecessary and believe it to be due to the inductance of said winding S.Itis seen from the above figures that the total length of the circuit AS A is six hundred feet, or equal to the full length of the wavetransmitted, and is determined by the constants of the circuit C P g.

In Fig. 2 the lengths of A L A are those given in connection withFig. 1. L in this instance is an inductive winding whose length isapproximately three hundred feet, or onehalf the Wave length of thereceived energy, A is one hundred and fifty feet, and A one hundred andfifty feet. In shunt to the Winding L is a Wave-responsive device WV,which is therefore at all times subjected to a maximum difference ofpotential existing at the terminals of the winding L. O is a condenserwhich serves to prevent the short-circuiting of the source of energy Bthrough said winding L. ff are the usual choke-coils, which areconnected in series with said wave-responsive device NV and the relay R,between whose windings is source of energy 1). Relay R controls a localcircuit in the well-known manner.

In Fig. 3 I have shown the same apparatus as in Fig. 1, except that thetail or lower conductor A is omitted and the secondary S is one hundredand fifty feet in length (nearly) in place of three hundred feet, as inFig. 1. In this instance, A is one hundred and fifty feet, and thereforethe entire circuit A S combined is three hundred feet, or one-half thelength of the wave as trans mitted.

In Fig. 4 the receiving device corresponds with that shown in Fig. 2,except that the winding L is one hundred and fifty feet in place ofthree hundred feet in length and the lower extension-conductor A isomitted. By this arrangement I have communicated signals betweenstations separated at least forty miles from each other and find that noearth connection whatsoever is required if the above proportions areobserved. I found also in my experiment that atmospheric disturbancessuch as those resulting from trolley-sparks and the like do notinterfere with my system to give false signals. The'probable explanationfor this resides in the fact that the electromagnetic wave emitted bythe inductive spark such as obtained from the trolley-circuitsand thelike is extremely short, and inasmuch as there is no ground connectionand the aerial conductor is of such dimensions as to respond only tomuch longer waves practically no difierence of potential is exerted atthe terminals of the Wave-responsive device,whereasin the case ofgrounded systems short electromagnetic Waves, as well as long ones, willbe conducted to the earth connections of the wave-responsive device andcause a false signal.

What I claim now, and desire to secure by Letters Patent, is-

1. In asignaling system, aconductor whose length is equal to that of thewave radiated therefrom and received thereupon.

2. In a wireless signaling system, a radiating or receiving conductor, awinding in series therewith and having a length approximately equal tohalf the length of the wave radiated therefrom or received thereupon.

3. In a wireless signaling system, a radiating or receiving conductor,comprising a winding having a length approximately equal to half thelength of the transmitted or received Waves, and a portion whose lengthis approximately one-quarter the length of the transmitted or receivedwaves.

4. In a wireless signaling system, an ungrounded conductor, comprisingin part a winding of a length approximately equal to one-half the lengthof the received or transmitted waves.

5. In a wireless signaling system, an ungrounded conductor, comprising awinding of a length approximately equal to one-half the length of thetransmitted or received waves, and a portion of a length approximatelyequal to one-quarter the length of the transmitted or received Waves.

6. In a wireless signaling system, a conductor comprising a winding of alength approximately equal to one-half the length of the received ortransmitted Waves, and having in addition a length approximately equalto or a multiple of a quarter wave length.

7. In a wireless signaling system, an oscillating circuit, atransformer-primary in said circuit, a radiating circuit comprising thesecondary winding of said transformer, the length of said winding beingapproximately equal to one-half the length of the transmitted Waves, anda conductor in said circuit of a length approximately equal to or amultiple of one-quarter wave length.

8. In a wireless signaling system, a transmitting or receiving conductorcomprising portions of lengths equal to one-quarter the length of thetransmitted or received waves, and a winding intermediate said portionsand of a length approximately equal to one-half the length of thetransmitted or received waves.

HARRY SHOEMAKER.

Witnesses:

G. S. EvEs, ALICE T. BURRAIGH.

